Anyone else using their EV as emergency home backup? Sharing what actually works

After last winter's grid outage (cheers, Storm Darragh), I finally stopped treating my Nissan Leaf as just a commuter and started treating it as a 24kWh battery on wheels. Paired it with a Victron MultiPlus-II and a proper V2H setup — kept the essentials running for nearly 18 hours without touching my rooftop solar reserves.

The numbers that surprised me: running fridge, a few LED circuits, and the router pulled roughly 300–400W average, so the usable chunk of the Leaf's pack goes much further than you'd expect. Obviously I'm not draining it to zero — keeping 20% in reserve so I can actually drive somewhere if things get properly grim.

Biggest headache so far is the CHAdeMO adapter situation — feels like Nissan owners are quietly being abandoned as the V2H ecosystem slowly pivots toward CCS. Anyone on here running a CCS-capable car (Ioniq 5, BYD, etc.) with a working V2H inverter solution in the UK that isn't eye-wateringly expensive?

@CornishNomad oh mate, Storm Darragh was the wake-up call for me too!

So my setup evolved a bit differently — I've got a shepherd's hut at the bottom of the garden that runs entirely off-grid anyway (Victron MultiPlus, Fogstar lithium bank), but when the main house lost power for nearly 14 hours last December I basically ran an extension cable from the hut like some kind of medieval peasant 😂

Been properly investigating V2H since then though. The problem with the Leaf is the CHAdeMO adapter situation — getting increasingly niche in the UK.

What converter are you actually using to get usable AC out of it? That's the bit I keep hitting a wall on. The garden office is crying out for a proper backup circuit and I'd rather not buy another battery bank if the car's just sitting there...

BenStewart | 47 posts

@CornishNomad great thread, Storm Darragh caught a lot of us out!

Worth flagging for anyone considering this — the Leaf's CHAdeMO port is key here, but newer EVs with CCS only are a different story. V2H inverters compatible with CCS are still pretty thin on the ground in the UK, so check your vehicle before buying kit.

Also worth considering your DNO notification obligations if you're feeding back through a proper V2H unit rather than just running appliances directly off an inverter. Some folks skip that step and technically shouldn't.

That said, even a simple setup — quality inverter clipped to the 12V with a DC-DC boost, or a dedicated V2H box — can keep your fridge, router and a few lights going for days. Real peace of mind over winter.

Narrowboat life means I'm basically doing this in reverse — my boat is the off-grid setup, and the van's the backup 😄

But Storm Darragh had me moored up with no shore power for 4 days, so I get it.

One thing nobody's mentioned — V2L capable EVs are proper game changers for this. My mate's Ioniq 5 just plugs straight in, no inverter faff. Wish more UK buyers knew to look for that spec when purchasing.

@CornishNomad which Victron MultiPlus are you running? Curious whether the 2000VA handles the Leaf's V2H output cleanly or if you're seeing any frequency issues. Had similar gremlins pairing non-native inverters with battery sources on the boat.

Chris1997 | 134 posts

Great thread @CornishNomad! I went down a similar rabbit hole after Darragh. I've got a 2019 Leaf (40kWh) and ended up going with a CHAdeMO-to-AC inverter route rather than the Victron path — bit fiddly to set up initially but once it clicked it's been rock solid.

One thing I'd add that nobody seems to mention: keep an eye on your Leaf's battery temperature before you start drawing heavy loads, especially in January. Mine got a bit grumpy one morning when it was minus 4 outside and I was trying to run the kettle and a small oil radiator simultaneously. Throttled back noticeably.

@BreezyDrifter that's a brilliant perspective actually — you've essentially solved the problem the other way round! What inverter are you running on the narrowboat?

VanAmy | 312 posts

@BreezyDrifter that's almost exactly my situation — narrowboat has 400Ah of Fogstar lithium as the primary system, van conversion acts as overflow/backup when I'm moored somewhere awkward. The two systems talking to each other via Victron Cerbo GX has been genuinely transformative.

One thing nobody's mentioned yet: bidirectional charging compatibility is everything. Not all Leaf years support CHAdeMO V2H properly — the 2018+ 40kWh models are far more reliable for it than the earlier 24kWh units. Worth checking your specific firmware version before investing in a proper V2H unit, as some need a dealer update first.

Also factor in battery degradation before leaning on it heavily for backup — a Leaf that's showing 10 bars might only have 18kWh usable, which changes your load calculations considerably.

@CornishNomad interesting timing on this thread — been mulling over exactly this for the tiny house build.

My concern with V2H as a backup strategy is the cycle degradation on older Leaf packs. The 24kWh gen1 batteries are already notorious for capacity loss, and hammering them with deep discharge cycles as a "free" UPS seems like a false economy long-term.

That said, if you're using a CHAdeMO-to-Victron setup and keeping discharge to say 20-80%, the maths probably still works in your favour compared to buying a dedicated battery bank.

Has anyone actually tracked state-of-health before/after a winter of doing this? Would be useful real data rather than theory. Wondering if a Fogstar Drift 10kWh as a buffer between the Leaf and the Multiplus might be the smarter architecture — take the cycling punishment so the EV pack doesn't have to.

DaleLover | 847 posts

My Leaf basically moonlights as a very expensive Fogstar battery that occasionally takes me to Tesco — the V2H rabbit hole is deep but the Victron integration is chef's kiss once you stop crying about the CHAdeMO adapter costs. @Thommo for a tiny house the maths is almost offensively good; 24kWh against a small load is basically a week's worth of "grid who?" — just mind your battery's state of charge floor or you'll be walking to Tesco instead of driving.